diff --git a/mod/lti/classes/event/unknown_service_api_called.php b/mod/lti/classes/event/unknown_service_api_called.php
index 7510f5dfff1..cf059cae5ee 100644
--- a/mod/lti/classes/event/unknown_service_api_called.php
+++ b/mod/lti/classes/event/unknown_service_api_called.php
@@ -44,16 +44,28 @@ defined('MOODLE_INTERNAL') || die();
  */
 class unknown_service_api_called extends \core\event\base {
 
-    /** Old data to be used for the legacy event. */
-    protected $legacydata;
+    /** @var \stdClass Data to be used by event observers. */
+    protected $eventdata;
 
     /**
-     * Set method for legacy data.
+     * Sets custom data used by event observers.
      *
-     * @param stdClass $data legacy event data.
+     * @param \stdClass $data
      */
-    public function set_legacy_data($data) {
-        $this->legacydata = $data;
+    public function set_message_data(\stdClass $data) {
+        $this->eventdata = $data;
+    }
+
+    /**
+     * Returns custom data for event observers.
+     *
+     * @return \stdClass
+     */
+    public function get_message_data() {
+        if ($this->is_restored()) {
+            throw new \coding_exception('Function get_message_data() can not be used on restored events.');
+        }
+        return $this->eventdata;
     }
 
     /**
@@ -99,7 +111,7 @@ class unknown_service_api_called extends \core\event\base {
      * @return mixed
      */
     protected function get_legacy_eventdata() {
-        return $this->legacydata;
+        return $this->eventdata;
     }
 
 }
diff --git a/mod/lti/service.php b/mod/lti/service.php
index cdf3148a766..beae870997e 100644
--- a/mod/lti/service.php
+++ b/mod/lti/service.php
@@ -146,15 +146,17 @@ switch ($messagetype) {
         //Fire an event if we get a web service request which we don't support directly.
         //This will allow others to extend the LTI services, which I expect to be a common
         //use case, at least until the spec matures.
-        // Please note that you will have to change $eventdata['other']['body'] into an xml
-        // element in an event observer as done above.
+        $data = new stdClass();
+        $data->body = $rawbody;
+        $data->xml = $xml;
+        $data->messagetype = $messagetype;
+        $data->consumerkey = $consumerkey;
+        $data->sharedsecret = $sharedsecret;
         $eventdata = array();
         $eventdata['other'] = array();
-        $eventdata['other']['body'] = $rawbody;
         $eventdata['other']['messageid'] = lti_parse_message_id($xml);
         $eventdata['other']['messagetype'] = $messagetype;
         $eventdata['other']['consumerkey'] = $consumerkey;
-        $eventdata['other']['sharedsecret'] = $sharedsecret;
 
         // Before firing the event, allow subplugins a chance to handle.
         if (lti_extend_lti_services((object) $eventdata['other'])) {
@@ -168,7 +170,7 @@ switch ($messagetype) {
 
         try {
             $event = \mod_lti\event\unknown_service_api_called::create($eventdata);
-            $event->set_legacy_data($eventdata);
+            $event->set_message_data($data);
             $event->trigger();
         } catch (Exception $e) {
             $lti_web_service_handled = false;
diff --git a/mod/lti/upgrade.txt b/mod/lti/upgrade.txt
new file mode 100644
index 00000000000..9e1ca22af30
--- /dev/null
+++ b/mod/lti/upgrade.txt
@@ -0,0 +1,6 @@
+This files describes API changes in the lti code.
+
+=== 2.7 ===
+
+* mod_lti\event\unknown_service_api_called now has less data stored in 'other'
+  but everything is still available for event observers via method get_message_data()